Effect of High Frequency Irradiation on the Energy Spectrum, Plasmons and Exchange Energy of Tilted Band 1T^'MoS₂

We have studied the effect of high-frequency electromagnetic dressing field on the dynamical polarization and collective excitations in tilted monolayer 1T^'MoS₂. The two energy gaps associated with up- and down- pseudospin renormalized in the presence of circularly polarized light irradiation. With the use of the Lindhard approach for the frequency-dependent polarizability propagator, we have developed a rigorous theoretical formalism for employing the Floquet energy spectrum for investigating the many-body effects on the plasmon excitations, their lifetimes due to Landau damping and the exchange energy under normal incidence of electromagnetic radiation at arbitrary temperature. The modified energy band and the dressed states corresponding to circularly polarized dressing field give rise to reduced polarization in the long wavelength limit and at the same time produce a distinctly different plasmon dispersion when compared to the plasmon spectrum in this regime in the absence of irradiation. Our calculations have shown that the presence of an energy band gap, the tilting, anisotropy, direct and indirect band gaps lead to a reduced exchange energy, which has some potential applications, such as, tunability of exciton polariton and plasmon excitations.